Which term describes heat transfer that occurs when two substances are in direct contact, with no intermediate medium?

Which term describes heat transfer that occurs when two substances are in direct contact, with no intermediate medium?

• A. Radiation
• B. Convection
• C. Absorption
• D. Conduction

Answer: (D)

Conduction describes heat transfer through direct contact between substances. When the hotter object touches the cooler one, its particles are more energetic and collide with neighboring particles, transferring some of their energy. This transfer happens at the interface and through the materials themselves, often aided by free electrons in metals. That's why a metal spoon becomes warm along its length when placed in hot soup—the energy moves from the soup into the spoon by direct interaction. In contrast, radiation is heat transfer through electromagnetic waves and can occur across empty space, convection requires the movement of a fluid, and absorption is about taking in energy rather than describing how heat moves between bodies.

Conduction describes heat transfer through direct contact between substances. When the hotter object touches the cooler one, its particles are more energetic and collide with neighboring particles, transferring some of their energy. This transfer happens at the interface and through the materials themselves, often aided by free electrons in metals. That's why a metal spoon becomes warm along its length when placed in hot soup—the energy moves from the soup into the spoon by direct interaction.

In contrast, radiation is heat transfer through electromagnetic waves and can occur across empty space, convection requires the movement of a fluid, and absorption is about taking in energy rather than describing how heat moves between bodies.